Thermal transitions in and structures of dried polyelectrolytes and polyelectrolyte complexes

Abstract

Dynamic mechanical analysis (DMA) was used to explore the thermomechanical properties of dried polyelectrolytes and polyelectrolyte complexes (PECs) with different thermal and humidity histories. Although differences in the amount of water remaining in polyelectrolytes and PECs were small for ambient versus dessicator storage, the properties of polyelectrolyte‐based materials were drastically different for different humidity histories. Glass transition temperatures (Tgs) of poly(diallyldimethylammonium chloride) (PDADMAC) were shown to vary by 100 °C, depending on humidity and thermal histories. These parameters also change glassy storage modulus values by 100%. Furthermore, we observe that dried PDADMAC is highly lossy. DMA of dried poly(styrene sulfonate) (PSS) was more complex and did not exhibit a glass transition in the tested range. DMA of a PEC of PDADMAC and PSS revealed a humidity history‐dependent water melt in the first heating cycle, as well as storage modulus values of dried and annealed PECs that only varied by 17–26% over a 275 °C temperature range. Based on these results, we report for the first time humidity history as controlling structure and properties of polyelectrolyte‐based materials. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 684–691

Precision Polyelectrolytes with Phenylsulfonic Acid Branches at Every Five Carbons

“…Two stages of decomposition are also seen with p 5PHS‐Li and p 5PhS‐Na with a trend of increasing thermal stability as the counter‐cation becomes larger. The degradation temperatures of p 5PhS‐Na are consistent with reports on the degradation of PSS‐Na under similar conditions . The increased thermal stability after neutralization can also be attributed to the removal of acidic protons, which can no longer catalyze the desulfonation reaction.…”

“…PSS is synthesized through the sulfonation of polystyrene (PS), which is a notoriously brittle (≈2% elongation at break) polymer with a high glass transition temperature ( T g ) of ≈100 °C . Upon sulfonation, the T g increases to a value higher than the thermal decomposition temperature ( T d ) which eliminates thermal processing and requires a higher degree of plasticization . Recently, our group reported the successful ring opening metathesis polymerization (ROMP) of 4‐phenylcyclopentene to high molar mass (>100 kg mol −1 ) and high conversions (>80%) .…”

Moldable Material from ε-Poly-l-lysine and Lignosulfonate: Mechanical and Self-Healing Properties of a Bio-Based Polyelectrolyte Complex

“…The strain at break of both complexes increased at higher relative humidity, whereas their maximum stress and Young’s modulus decreased. This behavior is consistent with those previously reported for PDADMACl/L-SO 3 Na 16,26,27 and other polyelectrolytes. 28 However, the water content in ε-PL-based complexes is lower than that of PDADMACl/L-SO 3 Na under comparable humidity.…”

Molecular Origin of the Glass Transition in Polyelectrolyte Assemblies

“…The strong correlation between PEC/PEM physical properties and water has been noticed elsewhere. 28 − 32 These effects are generally attributed to water plasticization and a lowering of the T g , but the underlying mechanism needs further explanation. 21 , 33 This is because PECs possess mixed ion pairing character (intrinsic and extrinsic), and the location of water molecules and their states have not been fully quantified.…”